I agree with you in part. I saw the movie, and it certainly appeared Stein did not take Panspermia seriously. I can’t put my finger on it, but I cam away with the impression that Stein believes God is the creator. Nonetheless, I don’t remember him saying that directly.
However, I have heard some ID theorists include Panspermia as one possible type of intelligent desgign, especially when distinguishing ID from creationism. ID theorists do not assume who, or what, the intelligent designer might be. (Of course, they all might hold personal beliefs as to who or what that designer would be, but this is not assumed under that theory.)
On the other hand, as I understand, at least some Panspermists (if that is even a word) will tell you that theirs is a third separate theory, partially because they do not want to be know as being members of the ID camp. (They’d probably lose their jobs if they did that.)
That's one of the reasons I think the movie is providing more heat than light. The movie leaves the impression that if it isn't being taught as an explicitly theistic philosophy, it isn't really ID. The ID proponents will submit on the surface that it's not about religion, but when it gets down to brass tacks, the only acceptable "designer" they'll accept is their own personal God.
——Panspermists——
Is that anything like ectoplasm? lol